Apparatus for forming aerated concrete slabs



Jan. 20, 1942- c. A. MARTIN APPARATUS FOR FORMING AERATED CONCRETE SLABS2 SheefrLs-Sheet l Filed Feb. 2, 1939 INTI llllllllllllllll llllllllllllll g llllll TIIIIHIIIIWIHHT ATTORNEYS Jan. 20, 1942. c. A.MARTIN APPARATUS FOR FORMING AERATED CONCRETE SLABS 2 Sheets-Sheet 2Filed Feb. 2, 1939 I ATTORNEYS Patented Jan. 20,1942

UNITED STAT es PATENT OFFICE APPARATUS FOR FORMING AERATED CONCRETESLABS 1 Claim.

This invention relates to aerated concrete slabs, and to the method andapparatus for producing-the same. More particularly, it relates totongue and groove concrete slabs of improved strength and of moreperfect form.

Aerated concrete slabs, usually provided with reinforcement such as ironor steel bars or rods, have come into extensive use as a buildingmaterlal. They combine the eminently desirable characteristics oflightness in weight and fireproofness. They are customarilymade inconvenient sizes, and then assembled in the building of which they forma part. In order to provide convenience and permanence in assembly, theymay be provided with tongues or grooves on all four sides.

Such labs are customarily manufactured in vertical molds, convenientlyprovided with a number of elongated parallel compartments to make aplurality of slabs at one time. This method combines both compactnessand ease of removal of the slabs from the molds. These molds are open atthe top, and are provided at the bottom and at the side edges withrecesses or projections in order to form the tongues and grooves.Immediately after the concrete is poured into themold, the top of suchmold is closed by placing thereon a cover which is provided on itsunderside with a recess or projectlon. This cover is pressed into thesoft concrete, forcing it into the recessor onto either side of theprojection, thus forming a tongue or groove in the top edge of theconcrete slab.

There are several disadvantages attendant upon the use of the devicespreviously described. In order to, obtain proper forming of the top edgeof the slab. and of the tongue or groove therein, it is required thatthe-mold be filled to a point within very precise limits, which isinconsistent with the type of material being handled in the mold. If theconcrete mix placed in the mold is relatively firm, the portions of thatmix down in the mold are liable to remain apart or, after the top coveris forced to position, to become dislodged and leave openings,

recesses or ragged portions in the top edge of the slab or in thelocking recess or projection thereon. .If the mix is relatively soft andfluid and if any slight excess quantity happens to be placed in themold, such excess will be forced upwardly and attempt to escape betweenthe mold cover and the mold. Also, due to the uneven and grittycharacter of the mix, portions of the mix the mold and distort the upperedge of the slab and its attendant groove or projection. If there is nota suflicient amount of material placed in the mold, the upper edge ofthe mold and its locking recess or projection will be weak or imperfect.

The present invention contemplates an apparatus and method wherebyconcrete mixes of widely varying consistencies may be readily moldedinto slabs of the type referred to with a maximum degree of uniformityin the shape, size and physical characteristics of the upper edge of theslab and its attendant groove or projection, and a method and apparatusin which no preciseness need be observed as to quantities of mixwithinthe mold and in which varying degrees of excess quantities of mix arereadily accommodated without any variation in the size of the slab orthe angularity of the upper edge or of the grooves or projectionstherein.

In the drawings! Fig. 1 is a plan view of a mold having a plurallty ofslab-forming compartments;

Fig. 2 is an elevation of a spacing member employed in the mold of Fig.1;

Fig. 3 is an enlarged fragmentary portion of Fig. 1, partly in crosssection;

Fig. 4 is a. perspective view of a tool for forming a groove in the topedge of a slab;

Fig. 5 is a slightly enlarged view taken along the line '55 of Fig. 3 atthe time the toolof Fig. 4 is being used to form a groove;

Fig. 6 is a view taken along the line 6-6 of Fig. 5; I

Fig. 7 is a perspective view of a finished slag, with parts broken awayfor convenience in viewing the internal structure; and

Fig. 8 is a perspective view of a tool for form- I ing a. tongue in thetop edge of a slab.

Referring to the drawings, a mold It) consists Between adjacent sets ofmembers l3, l4, l5 and 89 are removable partitions l6 dividing the moldwill adhere to the mold cover at certain points,

and will thus destroy the "level of the top of into a plurality ofcompartments II. In order to prevent deformation of the central portionsof the mold, spacing members I 8 are provided, said members havinggrooves 19 fitting into partitions IS. The entire mold may, if desired,rest upon a platform 9.

The walls and partitions of the mold III are preferably of steel sheetor other metal, according to the invention, and, as shown in thedrawings (see Fig. 5), it is desirable that the upper edges 38 of theside wall i2 and partitions iii of the mold be carefully constructed soas to provide trackways 38 in substantially uniform horizontal planes.In the event that the mold walls were made of wood or other readilydeformable material, the upper edges of the mold walls would be providedwith trackways of metal or other suitable material.

The tongue-forming members l4 and the groove-forming members are of acomplementary shape and preferably have tapering side walls of wellknown shape to aid in the fitting of the slabs together.

In the formation of slabs in such molds, reinforcements are first placedinside the mold. These conveniently consist of horizontal rods 3| andvertical rods 32 held together in the form of a very coarse and openmesh screen. The spacing members I8 are next put into place. An aeratedconcrete mix is then poured into each compartment so that the top of thepoured concrete is approximately on the same level in all compartments,this level being substantially that of the finished slab. This mix maybe relatively firm or relatively fluid. In the former case, it mayrequire rodding after pouring. The mass, if fluid when poured, is thenallowed to stand sufficiently long to receive an initial set," i. e., aset firm enough to retain a shape but not so firm but that the shape maynot be altered. If relatively firm when poured, no standing period maybe required. In this condition, the apparatus or tool shown in Fig. 4 isdrawn over the top of the setting concrete mass, as hereinafterdescribed.

This tool is indicated generally at 20, and consists of a body portion2|, of the same width as compartment I1, provided with a handle 22. The

upper part of this body portion is provided on each side with a lateralguiding shoulder 24. The bottom of the body portion 2| is also roundedupwardly, as shown at 28, at one or both ends. On the bottom of the bodyportion is a ridge 23 extending the length of said body portion and of across section similar to the cross section of the groove to be formed inthe concrete slab, and, therefore, preferably having tapering sides. Atone or both ends (at least at the same end as a rounded portion 28) thisridge tapers upwards and at the same time converges sideways to a point,as shown at- 25. The tool is preferably made of iron-or steel, in orderto secure weight and strength, although other materials may be used.

In order to secure the desirable results of this invention, this toolmust be pushed or drawn horizontally over the surface of the concrete.The leading end should be tapered as above described. By this means agroove 26 is formed and at the same time the concrete in the path of theridge, due to the tapering at 25, is compressed both downwardly and tothe sides, thus causing the concrete in the side walls 21 of the groove26 to become denser and thus stronger. If excess material is present inthe mold when poured, it will be compressed downwardly by means of therounded portion 28. If a large excess is present it will be pushed infront of the tool by the movement thereof and out at the ends of themold. Due to the sliding movement of the tool, which may be repeated anynumber of times, the side walls 21, the groove 26, and all surfacesthereof are perfectly and smoothly formed.

When the tool is used, the guiding shoulders 24 rest upon and are guidedby means of their cooperation with the trackways 38. The tool, whenmoved, is thus guided'in a true horizontal plane, and at the same timethe body portion 2| is confined between the partitions It, thuscentering the tool and causing the edge of the slab and its groove to bein a straight line.

The horizontal movement of the tool preferably extends throughout thelength of the slab. In order to accomplish this, the tops of the endwalls II are lower than the tops of the side walls I2 and partitions I6,being level with the bottom of the body portion 2| of the tool 20, andare provided with notches 33 of cross section similar outer side walls.

to that of the groove to be formed in the concrete. The tool 20 may thenstart and end its horizontal movement outside the mold, passing throughthe notches 33 in each case. If the concrete is relatively fiuid whenpoured, it may be necessary to temporarily close these notches until theconcrete has received its initial set.

After the groove in the top edge of the slab is thus formed, the slab isallowed to harden. When this has been accomplished, one of thepartitions I6 is lifted from the mold by means of hand hold 40. Thecompleted slab, indicated at 36 in Fig. 7, can then be easily removed.It is obvious, of course, that the spacing members l8 must be removedboth during the use of the tool 20 and the removal of the slab from themold.

It will be seen that no precise filling of the mold is required. Theonly requirement is that there be a minimum filling quantity or someexcess thereover. Preferably a slight excess is used, in order to secureuniformity in the slabs. In this case, as the tool is moved along on itstrackway across the mold it forces the excess material out at the endsof the mold. At the same time the tool exerts ample pressure upon theupper edge of the mass of mix so as to properly form that edge. Due tothe sliding movement of the tool on the trackway there is no chance forany material to remain lodged between the upper edges of the mold andthe tool to thereby deform the upper edge of the slab.

Instead of providing a tongue-forming recess at the bottom of the mold,a groove-forming projection may be provided at that point. In this case,the tool 20 is appropriately altered in shape, as in Fig. 8, where 34indicates a pair of ridges and other numerals correspond to similarnumerals identifying the tool shown in Fig. 3, to form a tongue on thetop edge of the slab instead of a groove. The words depression-formingtool," as .used throughout the specification and claim, are thereforeintended to cover a tool capable of forming a groove, or a tool capableof forming a tongue.

Obviously each mold may, if desired, consist of only a singlecompartment H. The expression mold," as used in the claims, maytherefore refer to one or more compartments. The expression.side walls,as used in the claim, is intended to cover either inner side walls(partitions) or It will be seen that the slab 36 thus formed will havethe top edge thereof of greater rather than lesser strength than therest of the slab, due to invention, it is not intended to be limitedexcept as defined in the appended claim.

I claim:

Apparatus for forming aerated concrete slabs having tongue and grooveedge formations, con i prising a mold having relatively flat parallelside walls, and end and bottom walls having formations for producingcomplementary tongue and groove formations at three edges of a slabbeing molded, and means for forming an element of a tongue and grooveformation in the top edge of a slab being molded and for cooperatingwith said side walls to compress the material adjacent the top edge ofthe slab, said means comprising an elongated block sl'idably supportedon said parallel side walls of the mold and having side edges receivedbetween said side walls, said block having its under surface incliningupwardly at the forward end thereof and said block having a formation onsaid under surface complementary to the formation to be produced in thetop edge of the slab, said formation on saidunder surface diminishing incross section toward the forward end of said block, thereby constitutinga sled-like deflector adapted to produce the required formation in theslab edge and to cooper-- ate with said upwardly inclined portion of theunder surface and with said side walls of the mold to compress thematerial adjacent the upper edge of the slab and to push forwardly thematerial in excess of the amount required for compression when the blockis slid on said parallel side walls.

CHARLES A. MARTIN

